Giving hospitalized Covid patients blood plasma transfusions from virus survivors may reduce their risk of dying after all, scientists now say.
The doctors had hoped that infusions of convalescent plasma – a straw-colored liquid in the blood that contains antibodies – could help the infected to recover.
However, a number of studies showed that the treatment does not increase survival rates, which led the World Health Organization to recommend that it be used only for seriously ill patients.
Now, researchers in New York have found that those treated with the therapy were 15 percent less likely to die within four weeks.
Patients at greatest risk for coronavirus, such as those battling diabetes or heart disease, benefited even more from the treatment, the team said.
The experts examined the results of eight existing studies, which involved more than 2,000 Covid patients.
They argued that older trials were too small to notice the effect of the treatment, which has been used to treat infections for at least a century.
Professor Andrea Troxel, head of research and biostatistician at NYU Langone Health, said: ‘Overall, our results show that patients admitted with Covid can benefit modestly from convalescent plasma.
“Patients with concomitant disease were most likely to show improvement from convalescent plasma, probably because they have the most difficulty in producing antibodies to fight their infection.
‘The infused plasma boosts their body’s ability to fight the virus, but only in the early stages of the disease and before the disease overwhelms their body.’
In the UK, trials of convalescent plasma as a Covid treatment were suspended after scientists said the results did not show that the treatment helped moderately ill people.
But the treatment is given to inpatients in the United States who have suppressed the immune system.
Reconvalent plasma (pictured) – the main component of blood containing antibodies and other immune cells needed to fight the infection – taken from Covid survivors may reduce the risk of patients dying, NYU researchers said
WHAT IS CONVALESCENT PLASMA AND WHERE IS IT USED?
Convalescent plasma has been used to treat infections for at least a century, dating back to the Spanish disease pandemic of 1918.
It was also tested during the 2009-2010 H1N1 influenza virus pandemic, the 2003 SARS epidemic and the 2012 MERS epidemic.
Convalescent plasma was used as a last resort to improve the survival rate of patients with SARS whose condition continued to worsen.
It has been shown to be ‘effective and life-saving’ against other infections, such as rabies and diphtheria, said Dr. Mike Ryan of the World Health Organization.
“This is a very important area to pursue,” said Dr. Ryan.
What is blood plasma?
Blood plasma is a straw-colored fluid that transports red and white blood cells and platelets (which trigger blood clots) around the body.
It also contains antibodies to fight viruses, including Covid in those who have recovered from an infection.
Doctors had hoped that the antibodies in the plasma would help Covid patients recover from the disease.
How does it work?
Blood banks take plasma donations just as they take donations of whole blood; plain plasma is used in hospitals and emergency rooms every day.
If someone only donates plasma, their blood is drawn through a tube, the plasma is separated and the rest is infused back into the donor’s body.
The plasma is then tested and purified to make sure it does not contain blood-borne viruses and is safe to use.
For Covid research, people who have recovered from the virus would donate.
NYU researchers examined data from eight different studies – conducted in the United States, Belgium, Brazil, India, Spain and the Netherlands – to assess the effectiveness of treatment.
The studies included 2,341 people admitted with Covid, who were 60 years old on average and received an injection of blood plasma.
Plasma is the largest component in blood, accounting for 55 percent of it, and contains antibodies.
The team found that those who received the treatment shortly after being admitted were 15 percent less likely to die within a month compared to those who did not receive it or received a placebo transfusion.
The study, published JAMA Network Open, contradicts previous findings that the therapy is ineffective or of limited value.
Imperial College London stopped their trials of treatment last year after data on nearly 1,000 patients showed that ‘no evidence’ of convalescent plasma increased survival rates.
And Oxford University researchers followed suit last year after an analysis of 1,800 deaths among 10,400 patients showed it “made no significant difference”.
Subsequently, WHO advised physicians to limit treatment to serious and critical patients only as part of clinical trials.
The agency, which examined 16 trials with more than 16,000 patients, concluded that treatment does not improve the survival rate or reduce the risk of a patient needing a ventilator. Managing is also expensive and time consuming.
However, it said that critically ill patients can benefit from it, so clinical trials with the treatment should continue.
But Professor Troxel said that aggregating results from several studies shows the benefits of the treatment, as the others were too small to show its impact on subgroups of patients.
Research researcher Dr. Mila Ortigoza said that convalescent plasma collected from previously infected and subsequently vaccinated donors would contain high levels of antibodies that could protect against future mutations of the virus.
So convalescent plasma can offer faster and more robust treatment against Covid’s variants than other therapies that ‘tend to become less effective over time and have to undergo a redesign process to address a new variant, such as monoclonal antibody treatments,’ she said.
Research co-researcher Professor Eve Petkova, a public health expert at the university, said the team uses the results to create a scoring system that makes it easier for doctors to calculate who benefits most from treatment.
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